1. Field of the Invention
The present invention relates to a medical therapeutic and/or diagnostic appliance with an arrangement which senses its position and attitude at any given time and which comprises a first sensing unit on the therapeutic and/or diagnostic appliance, and a second sensing unit having a fixed location and attitude and arranged to be separated from the first sensing unit by a signal path.
2. Description of Prior Art
Such a therapeutic and/or diagnostic appliance is known, for example, from U.S. Pat. No. 5,408,409. This document shows as the first sensing unit a LED arrangement on the therapeutic appliance, embodied as a surgical cutting instrument, and spaced from it, a camera arrangement having a fixed location and attitude as the second sensing unit.
The prevention of infection is of great importance in medicine. Medical therapeutic and/or diagnostic appliances must therefore be sterilizable. Thus the therapeutic appliance known from U.S. Pat. No. 5,408,409 is surrounded, together with the first sensing unit which is fixedly attached to it, by a sterile sheath during an operation. An effective and reliable sterilization of the medical therapeutic and/or diagnostic appliances, which usually do not have a uniform, smooth surface, is thereby ensured, whereas it can only be achieved with difficulty by solely spraying with a sterilizing solution. On the other hand, however, sheathing the first sensing unit can lead to problems of reliability and accuracy of position and attitude sensing, with regard to achieving the most undistorted signal paths between the first and the second sensing unit, since a sterilizing sheath can interfere with the signal transmission between the first and the second sensing unit.